Endotracheal tubes are widely used in anesthesia and critical care medicine. The endotracheal tube provides access to the upper airways for controlled, assisted ventilation or spontaneous unassisted ventilation with positive end expiratory pressure.
One of the drawbacks of inserting an endotracheal tube into an upper airway of a patient results in the reduction of the lumen of the airway. One manner in which the lumen is reduced is the inability to use the largest possible endotracheal tube for a given patient without subjecting the patient to increased risks. Generally, it is not advisable to insert the largest possible endotracheal tube in the patient since such an attempt will entail many trials and errors which may take additional time, such additional time to be avoided, especially in critical care situations.
In addition, and to maintain endotracheal wall stability, the wall thickness is required having sufficient strength to be safely handled by the using physician or technician. At present, adult endotracheal tubes range between 7 to 9 millimeters in internal diameter, the total wall thickness ranging between 1.4 and 1.5 millimeters. For newborn endotracheal tubes, the decrease in lumen internal diameter as a result of the required wall thickness amounts to approximately 0.5 millimeters or more.
Any decrease in the lumen due to wall thickness has a profound effect on the airway resistance, since the resistance to air flow is inversely proportional to the fourth power of the radius.
As a result of the deficiencies in prior art endotracheal tubes, a need has developed to provide an endotracheal tube having reduced airway resistance so as to facilitate establishment of artificial airways other than those using mechanical ventilators.
Conventional technology used in the fabrication of blood catheters uses either extrusion or dip coating onto mandrels. Extrusion technology has the advantage of low cost, but has little flexibility. With extrusion, the resulting thin wall catheters are rather stiff and are liable to kink or bend to obstruct the inner passageway. The dip coating technique used for currently available catheters and tubes is not reproducible in thin wall gauges and, therefore, wall thickness remain substantial.
In response to this need, the present invention provides an ultra thin walled wire reinforced endotracheal tube which provides reduced airway resistance to permit easier breathing by a patient. The ultra thin walled endotracheal tube comprises a polymer having incorporated therewith a stainless steel spring material to form a continuous tubing. The combination of the polymer and stainless steel spring material provides an ultra thin wall of the tubing which permits the use of an endotracheal tube having similar diameters as prior art tubings but with increased internal diameters and resultant reductions in airway resistance.